class Solution:
    def climbStairs(self, n: int) -> int:
        dp = [1]*(n+1)
        for i in range(2, n+1):
            dp[i] = dp[i-1] + dp[i-2]
        return dp[n]

if __name__ == '__main__':
    s = Solution()
    print(s.climbStairs(1))
    print(s.climbStairs(2))
    print(s.climbStairs(4))
    print(s.climbStairs(10))    